Bid Ask Spread in Indian Markets: What It Really Costs You

What the Bid Ask Spread Actually Is on the NSE

Open the market depth window for any NSE stock and you see two columns. On the left are bid prices, the highest amounts buyers are currently willing to pay. On the right are ask (also called offer) prices, the lowest amounts sellers are willing to accept. The single best bid and the single best ask sit at the top. The bid ask spread is simply the best ask minus the best bid at that instant. If the best bid for Infosys is Rs 1,540.20 and the best ask is Rs 1,540.45, the spread is 25 paise.

This number matters because of how orders fill. A market order to buy lifts the best ask, so you pay the higher price immediately. A market order to sell hits the best bid, so you receive the lower price. The spread is therefore the instant round trip cost of buying and selling at the same moment. It is not charged by your broker or the exchange. It is the price you pay the market for the convenience of trading right now instead of waiting.

On the NSE this is not a free floating number. SEBI and the exchange enforce a minimum tick size of 5 paise (Rs 0.05) for most equity scrips. Prices can only move in 5 paise steps, so the narrowest possible spread is exactly one tick, 5 paise. A liquid stock spends most of the session at a one tick or two tick spread. An illiquid stock can have nobody quoting near the last price at all, which is where spreads blow out to rupees.

Liquid vs Illiquid Stocks: The Real Spread in Paise

The single most useful thing to understand is how dramatically the spread changes between a heavily traded large cap and a thin small cap. The table below shows illustrative intraday spreads for Indian stocks across the liquidity ladder. Exact values change second to second, but the orders of magnitude are real and stable. Notice that the spread in rupees can look similar, but the spread as a percent of price, which is what actually costs you, varies by a factor of 50 or more.

Read the last column, not the rupee column. On HDFC Bank you give up about 0.003 percent to cross the spread, which is almost nothing. On the illiquid micro cap you hand over more than 4 percent the instant you complete a round trip, before a single rupee of brokerage or STT. That micro cap stock has to move more than 4 percent in your favour just to break even on the spread alone. This is why experienced Indian traders treat wide spreads as a cost trap, not a hidden gem.

• Index heavyweights (Reliance, HDFC Bank, TCS, Infosys, ICICI Bank): usually 5 to 25 paise, often pinned to the 5 paise tick.
• Nifty 50 and Nifty Next 50 names in general: a few paise to a few tens of paise.
• Mid caps with daily volume in the lakhs of shares: tens of paise, roughly 0.05 to 0.2 percent.
• Thin small and micro caps, illiquid PSU and penny names: 50 paise to several rupees, often 0.5 to 5 percent.
• Stocks in circuit or with very low free float: the spread can effectively be infinite when only one side is quoting.

Worked Example: What the Spread Costs You in Rupees

Numbers below are illustrative and not a recommendation or a promise of any return. Suppose you want to buy 100 shares of Reliance for an intraday trade. The best bid is Rs 1,419.90 and the best ask is Rs 1,420.00, so the spread is 10 paise. You send a market buy and get filled at Rs 1,420.00, paying Rs 1,42,000 for 100 shares. If you immediately changed your mind and sold at market, you would hit the best bid of Rs 1,419.90 and receive Rs 1,41,990.

The spread cost of that instant round trip is Rs 1,42,000 minus Rs 1,41,990, which is Rs 10. That is the 10 paise spread times 100 shares. On a 1.42 lakh position, Rs 10 is trivial, about 0.007 percent. Now run the same trade on the illiquid micro cap from the table, buying 100 shares at Rs 43.00 against a bid of Rs 41.20. The spread is 180 paise, so the round trip spread cost is Rs 1.80 times 100, which is Rs 180 on a position of only Rs 4,300. That is over 4 percent gone before fees.

The lesson scales with frequency. An intraday scalper doing 20 round trips a day on Reliance sized at 100 shares pays roughly 20 times Rs 10, which is Rs 200 a day in spread cost alone, on top of brokerage, STT and exchange charges. Over 250 trading days that is about Rs 50,000 a year, purely from crossing the spread. The same activity on the micro cap would cost Rs 3,600 a day, which would quietly destroy the account. Liquidity is not a nice to have. It is the difference between a viable strategy and a guaranteed loss.

• Spread cost on one round trip = spread in rupees x quantity. On 100 Reliance shares at a 10 paise spread that is Rs 10.
• Spread cost scales linearly with how many times you trade. Frequency, not size, is what makes a small spread expensive.
• Brokerage, STT and exchange fees are extra and separate. The spread is the cost the market charges you, the rest is what the broker and government charge.
• On equity intraday, remember STT of 0.025 percent applies on the sell side, plus brokerage and 18 percent GST on brokerage. The spread is on top of all of that.

Spreads in Nifty and Bank Nifty Options

In the F&O segment the spread story is sharper because options have hundreds of strikes, and liquidity is concentrated at the money. For weekly Nifty options near the at the money strike, the spread is often just 25 to 50 paise of premium. As you move to deep out of the money or far month strikes, the same option might show a 2 to 5 rupee spread, or wider, because almost nobody is quoting there.

Here is an illustrative example. The Nifty lot size is 65. You buy one lot of an at the money weekly call where the best bid is Rs 120.00 and the best ask is Rs 120.50, a 50 paise spread. Crossing it on a market order costs 0.50 times 75, which is Rs 37.50 for the round trip, small relative to the roughly Rs 9,037 premium outlay. Now take a deep out of the money call where the bid is Rs 3.00 and the ask is Rs 6.00, a 3 rupee spread. Crossing that costs 3.00 times 75, which is Rs 225, and the option premium itself might only be Rs 6. You would need the option to nearly double just to recover the spread. This is exactly why selling or buying illiquid far strikes is so punishing.

Why Spreads Widen: The Drivers You Can Actually Watch

Spreads are not random. They widen and tighten for understandable reasons, and once you can read them you can time your entries to avoid the worst conditions. The biggest single driver is liquidity, the number of active buyers and sellers. The more orders resting in the book, the tighter the best bid and ask sit. Nifty 50 heavyweights have thousands of participants quoting continuously, so their spreads are pinned to the tick almost all day.

The second driver is time of day. Spreads are widest in the first few minutes after the 9:15 open and again near the 3:30 close, when uncertainty is high and order books are thin. They are tightest in the calmer mid session. Spreads also blow out around scheduled events such as RBI policy, the Union Budget, quarterly results and index expiry, when participants pull their quotes to avoid being caught on the wrong side of a sudden move. During the post results gap on a single stock, even a normally liquid name can show a temporarily wide spread until two way flow returns.

• Liquidity and volume: more participants means a tighter spread. This is the dominant factor.
• Time of day: widest at open and close, tightest mid session.
• Volatility and events: RBI policy, Budget, results and expiry days widen spreads as quotes thin out.
• Price level and tick size: a 5 paise tick is a bigger percent of a Rs 40 stock than a Rs 4,000 stock, so cheap stocks have structurally wider percentage spreads.
• Free float and circuit limits: low float or circuit bound stocks can have one sided books and effectively no usable spread.

Spread vs Slippage vs Impact Cost

Traders often blur three related ideas. The spread is the gap between the best bid and best ask for the very first share. Slippage is the difference between the price you expected and the price you actually got, which usually happens when your order is larger than the quantity available at the best price. Impact cost, a term the NSE itself publishes, measures how much the price moves against you when you execute a standard order size, and it is the cleanest single number for comparing liquidity across stocks.

Why this matters: a stock can show a narrow best bid ask spread of 5 paise but still cost you dearly if only 50 shares are available at that price and you want 5,000. Your order eats through several price levels, and your average fill price is far worse than the top of book suggested. The headline spread told you the cost of trading one share, not your whole position. For any sizeable order, check the depth of the book, not just the top line spread.

How SEBI and the NSE Shape the Spread

Two structural rules set by SEBI and the exchange define the floor for spreads in India. The first is the tick size. By mandating a minimum price increment of 5 paise for most equities, the exchange guarantees the spread can never be tighter than one tick. For very low priced stocks the exchange uses a finer tick so the percentage cost stays reasonable. The second is the framework for market makers and liquidity providers, especially in newly listed scrips, ETFs and some derivatives, where designated participants are required to quote both sides continuously to keep spreads usable.

SEBI also influences spreads indirectly through the surveillance and circuit breaker system. Price bands and the Additional Surveillance Measure (ASM) and Graded Surveillance Measure (GSM) lists restrict trading in volatile or manipulation prone stocks. When a stock is moved into a trade for trade segment or hit with tighter price bands, two way liquidity often dries up and spreads widen. So a wide spread can itself be a flag that a stock is under surveillance or has thin genuine interest, which is useful risk information before you commit capital.

Practical Ways to Pay Less Spread

You cannot remove the spread, but you can control how much of it you pay. The single biggest lever is the order type. A market order always crosses the spread, paying the ask when buying and receiving the bid when selling. A limit order placed at the bid (when buying) or the ask (when selling) lets you try to capture the spread instead of paying it, at the cost of the order possibly not filling. For patient entries in liquid stocks, limit orders quietly save real money over a year.

Beyond order type, stick to liquid instruments, trade away from the volatile open and close, avoid sizing up in thin strikes, and always look at market depth before sending a large order. For options, prefer at the money and near month strikes where the book is deep. If you must trade an illiquid name, break the order into smaller pieces and use limit prices so you are not forced to eat several price levels at once.

• Use limit orders instead of market orders wherever you can wait a few seconds for a fill.
• Trade liquid names and at the money option strikes where the spread is one or two ticks.
• Avoid the first and last few minutes of the session unless you specifically need them.
• Check market depth, not just the top of book spread, before placing a large order.
• Split big orders in illiquid stocks into smaller limit orders to limit slippage and impact cost.
• Track your spread and fee cost in a trading journal so you can see the true drag on returns.

Sources and Further Reading

For authoritative data and current contract specifications, refer to NSE India, Zerodha Varsity and SEBI. Tick sizes, lot sizes, STT rates and surveillance lists change over time, so always confirm the current rules and contract specs on the official source before you trade. The numbers in this guide are illustrative and are not investment advice or any promise of returns.

Sources and Further Reading

For authoritative data and further reading on this topic, refer to NSE India, Zerodha Varsity and SEBI (Securities and Exchange Board of India). Always confirm current rules, rates and contract specifications on the official source before you trade.